NEW ORLEANS (AP) â€” A woman claimed to have rescued a baby from carjackers at a convenience store, but she turned out to be a relative of a car thief who had asked for help when he discovered a baby in the back seat of the stolen car, police said Thursday.

The baby's mother had left her keys and her 19-month-old daughter in her 2006 Nissan Altima when she went into a convenience store in Picayune, Miss., around 8 p.m. Wednesday, said Sgt. Joe Narcisse, a spokesman for the New Orleans Police Department.

He said police in Picayune knew the alleged thief's name and location almost from the start â€” he had left his girlfriend's car behind when he stole the Altima. The girlfriend gave investigators his name and cell phone number. Investigators said he was Corey Rankin, 24, of New Orleans.

New Orleans police found Rankin riding a bicycle early Thursday and arrested him, Narcisse said.

Meanwhile, a woman claiming to be a convenience store clerk called New Orleans police, saying she overheard carjackers talking about a baby in a car. She claimed that she sneaked the baby out of the car while the men were in the store.

She gave the child to police about 10:30 p.m., and the baby was reunited with her parents before 11 p.m., Narcisse said. During their investigation, he said, they learned that Rankin had called her after he realized the baby was in the car, asking her to take the child and return it.

"This lady, his aunt, she's not even a clerk there. This is just the story she and Rankin devised," Narcisse said.

The woman, whose name he did not release, could face charges of lying to police or accessory after the fact, he said.

"We're still pretty pleased that she did the right thing by turning in the baby," he said.